Some areas seem to be more private than others, but there's no practical way to know for sure. The island is dotted with thousands of security cameras, operated by the police, shops, and office towers. A couple of groups have tried to count those that are visible, and their results suggest somewhat lighter surveillance far uptown, with the exception of Columbia University and parts of 125th Street. In comparison, Times Square, Greenwich Village, SoHo, and the Financial District are riddled with cameras. (Shutter-shy New Yorkers downtown are best off in the Lower East Side.) But there are hundreds, and perhaps thousands, more cameras concealed behind tinted windows, or tucked inside of lobby smoke detectors, clocks, and sprinklers that are not included in these counts.

In 2005, the New York Civil Liberties Union conducted the most intense camera count (PDF), but focused mainly on Lower Manhattan. The group counted 4,176 cameras below 14th Street, an area about one-sixth the size of the island. That's up 443 percent from 1998, when the group conducted its first study. Greenwich Village and SoHo offered the least privacy, with a rate of three cameras per acre, or one for every 84 residents.

A group called the Institute for Applied Autonomy has merged some of their own research with the NYCLU data to create an interactive, Web-based map of Manhattan's cameras. The program will even give you the path of least surveillance between any two points. The database isn't frequently updated, however, and there's reason to believe Manhattan's camera-count is on the rise. As of 2006, for example, all nightclubs in the City are required to have security cameras posted at their entrances and exits. (Some clubs boast a camera for every 200 square feet.) In 2006 and 2007, the New York Police Department installed hundreds of additional cameras in Lower Manhattan and recently announced plans to extend the project into Midtown. The initiative is based on London's Ring of Steel, which launched in the 1990s in response to IRA bombings. Britons may be the most videotaped people on earth. London has some 500,000 security cameras, while Great Britain as a whole has about 4 million.

Not all surveillance cameras raise the same privacy concerns. In many apartment buildings, the cameras broadcast to the doorman via closed-circuit television but don't record. Others keep their data on one-day, one-week, or one-month loops, recording over the prior period unless there is a need to preserve the video. (Private camera operators are entitled to withhold their recordings from police in the absence of a subpoena, but they almost always hand over footage without a fight.) Some cameras stay fixed on one field, while others sweep back and forth automatically. The tinted semicircles on walls and ceilings usually contain cameras that a security agent can pan, tilt, and zoom. These operator-controlled cameras occasionally get the police into trouble. One study in England found that camera operators disproportionately focused on young black males and frequently followed women for "voyeuristic" reasons. New York police taped a couple having sex on a rooftop for four minutes in the days before the 2004 Republic National Convention.

Police-owned cameras typically have excellent resolution. Some are capable of reading license plates from a mile away in low light or a text message from one story above. But most surveillance cameras are often damaged, out-of-date models with lousy pictures.